1. Field of the Invention
The present invention relates to a fluorescence observation apparatus, and more particularly, to a fluorescence observation apparatus for observing fluorescent light beams emitted from a plurality of fluorescent substances.
2. Description of the Related Art
Cancer diagnosis techniques using molecular targeting agents are becoming a focus of attention in recent years. To be more specific, for example, a technique of scattering or injecting a fluorescent probe (fluorescence agent) targeting at biological protein that is developed specifically in cancer cells and then identifying the presence/absence of cancer based on fluorescent light emitted from the target region is under study in recent years. Such a technique is useful for early detection of cancer in the field of the digestive tract.
Furthermore, as an application of the aforementioned technique, a technique is being proposed which is designed to scatter or inject a plurality of types of fluorescent probes into a target region of a living body and observe the developed state of a plurality of types of biological protein corresponding to the plurality of types of fluorescent probes in a composite manner based on fluorescent light of a plurality of wavelengths emitted from the target region. Such a technique is considered useful for estimation of stages of cancer, prediction of risk of cancer invasion and prediction of risk of cancer metastasis or the like.
For example, Japanese Patent Application Laid-Open Publication No. 2008-161550 and Japanese Patent Application Laid-Open Publication No. 2008-148791 disclose an endoscope system that makes observations by scattering or injecting a plurality of types of fluorescent probes into a target region of a living body, configured to be able to acquire a fluorescence image (image of a fluorescent light distribution) for each fluorescent probe by carrying out calculation processing based on a relationship between the intensity of fluorescent light and concentration of the fluorescent probe obtained during the observations.